Preheat the oven to 400 degrees F. In a small bowl, soak Grape-Nuts cereal in milk until all the milk is absorbed and the cereal is moist. Set aside.
Once cereal is moistened, combine turkey, Parmigiano-Reggiano, parsley, shallot, tomato paste, egg, garlic, salt, pepper, and moistened cereal in a large bowl. Using fingers, gently mix all the ingredients until thoroughly combined.
Using a small ice cream scoop or meat baller, form the meat mixture into 1 1/2-inch balls (24 meatballs). Place the meatballs on baking sheet covered in non-stick foil. Bake 15 minutes or until cooked through.
While the meatballs are cooking, prepare the pesto sauce. In a food processor, place basil leaves, Parmigiano-Reggiano cheese, pine nuts, and garlic. Pulse several times to combine. With the food processor running, slowly add the olive oil in a steady stream. Season with salt and pepper, to taste.
Using a spiralizer, cut each zucchini into “noodles.” In a large saucepan, gently warm the pesto sauce, zucchini noodles, and tomatoes.
When ready to serve, divide the noodles into serving bowls. Top with turkey meatballs. Garnish with freshly grated Parmigiano-Reggiano cheese and a sprig of fresh basil.